Association between non-high-density lipoprotein cholesterol to high-density lipoprotein cholesterol ratio and cardiometabolic multimorbidity among middle-aged and older adults in China

Background The ratio of non-high-density lipoprotein cholesterol (non-HDL-C) to high-density lipoprotein cholesterol (HDL-C) (NHHR) served as a novel comprehensive lipid indicator. This study aimed to explore the association between NHHR and the incidence of cardiometabolic multimorbidity (CMM). Methods This study included 8191 individuals from the China Health and Retirement Longitudinal Study (CHARLS) database. We used multivariable cox proportional hazards regression, logistic regression, and restricted cubic splines (RCS) analysis to evaluate the association between NHHR and CMM. Subgroup analyses and interaction tests were also performed. Results The incidences of CMM among participants in quartiles (Q) 1-4 of NHHR were 7.03%, 8.3%, 10.06%, and 16.55%, respectively. The NHHR was significantly higher in individuals with CMM compared to those without CMM (P < 0.001). When assessed as a continuous variable, NHHR was independently associated with the risk of CMM, as demonstrated by both multivariable cox proportional hazards regression analysis (HR = 1.05, 95% CI = 1.02-1.07, P < 0.001) and logistic regression analysis (OR = 1.09, 95% CI = 1.04-1.15, P < 0.001). Compared to individuals in the lowest quartiles of the NHHR (Q1), the risk of CMM in the highest quartiles (Q4) was increased by 1.25-fold according to multivariable cox proportional hazards regression analysis (HR = 2.25, 95% CI = 1.73-2.93, P < 0.001) and by 1.48-fold according to logistic regression analysis (OR = 2.48, 95% CI = 1.86-3.31, P < 0.001). This association was consistent across nearly all subgroups. RCS analysis revealed a significant nonlinear association between NHHR and CMM. Additionally, the predictive ability of NHHR for CMM was 0.613, which was superior to that of both HDL-C and non-HDL-C (P < 0.05). Furthermore, the composite variable comprising NHHR and other traditional risk factors exhibited the highest predictive value (C statistic = 0.679). Conclusion A higher NHHR was closely associated with an increased risk of CMM. Further studies on NHHR could be beneficial for preventing and treating CMM.